package com.gl.basis.zuul.util;

import org.apache.commons.codec.binary.Base64;

import java.io.*;

public class Base64Utils {

	/**
	 * 文件读取缓冲区大小
	 */
	private static final int CACHE_SIZE = 1024;

	/**
	 * <p>
	 * BASE64字符串解码为二进制数据
	 * </p>
	 * 
	 * @param base64
	 * @return
	 * @throws Exception
	 */
	public static byte[] decode(String base64) throws Exception {
		return new Base64().decode(base64);
	}

	/** */
	/**
	 * <p>
	 * 二进制数据编码为BASE64字符串
	 * </p>
	 * 
	 * @param bytes
	 * @return
	 * @throws Exception
	 */
	public static String encode(byte[] bytes) throws Exception {
		return new Base64().encodeToString(bytes);
	}

	/**
	 * <p>
	 * 将文件编码为BASE64字符串
	 * </p>
	 * <p>
	 * 大文件慎用，可能会导致内存溢出
	 * </p>
	 * 
	 * @param filePath 文件绝对路径
	 * @return
	 * @throws Exception
	 */
	public static String encodeFile(String filePath) throws Exception {
		byte[] bytes = fileToByte(filePath);
		return encode(bytes);
	}

	/** */
	/**
	 * <p>
	 * BASE64字符串转回文件
	 * </p>
	 * 
	 * @param filePath 文件绝对路径
	 * @param base64   编码字符串
	 * @throws Exception
	 */
	public static void decodeToFile(String filePath, String base64) throws Exception {
		byte[] bytes = decode(base64);
		byteArrayToFile(bytes, filePath);
	}

	/** */
	/**
	 * <p>
	 * 文件转换为二进制数组
	 * </p>
	 * 
	 * @param filePath 文件路径
	 * @return
	 * @throws Exception
	 */
	public static byte[] fileToByte(String filePath) {
		byte[] data = new byte[0];
		File file = new File(filePath);
		if (!file.exists()) {
			return data;
		}

		FileInputStream in = null;
		ByteArrayOutputStream out = null;
		try {
			in = new FileInputStream(file);
			out = new ByteArrayOutputStream(2048);
			byte[] cache = new byte[CACHE_SIZE];
			int nRead = 0;
			while ((nRead = in.read(cache)) != -1) {
				out.write(cache, 0, nRead);
				out.flush();
			}

			return out.toByteArray();
		} catch (Exception e) {
			throw new RuntimeException(e);
		} finally {
			if (out != null) {
				try {
					out.close();
				} catch (IOException e) {
				}
			}

			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
				}
			}
		}

	}

	/**
	 * <p>
	 * 二进制数据写文件
	 * </p>
	 * 
	 * @param bytes    二进制数据
	 * @param filePath 文件生成目录
	 */
	public static void byteArrayToFile(byte[] bytes, String filePath) {
		InputStream in = new ByteArrayInputStream(bytes);
		File destFile = new File(filePath);
		if (!destFile.getParentFile().exists()) {
			destFile.getParentFile().mkdirs();
		}

		OutputStream out = null;
		try {
			destFile.createNewFile();
			out = new FileOutputStream(destFile);
			byte[] cache = new byte[CACHE_SIZE];
			int nRead = 0;
			while ((nRead = in.read(cache)) != -1) {
				out.write(cache, 0, nRead);
				out.flush();
			}
		} catch (Exception e) {
			throw new RuntimeException(e);
		} finally {
			if (out != null) {
				try {
					out.close();
				} catch (IOException e) {
				}
			}

			if (in != null) {
				try {
					in.close();
				} catch (IOException e) {
				}
			}
		}
	}

}
